José Vázquez-Cabo

Synthesis and characterization of Cu-doped polymeric carbon nitride

ABSTRACT Polymeric carbon nitride doped with copper through a solid-state reaction was characterized by several techniques, among them are UV-visible spectroscopy, infrared spectroscopy, X-ray photoelectron spectroscopy, etc. The material is a semiconductor with a wide band gap of 2.74 eV. Sites of both Cu(I) and Cu(II) were detected, apparently only coordinated by the polymer. The material comprises crumpled nanosheets, and is substantially an amorphous layered material with a prevalent 2D structure with low inter-planar interactions, as shown by X-ray diffractometry and TeraHertz spectroscopy. Photo-oxidation of benzyl alcohol was used to probe the active sites of the material, comparing them with the non-doped material. The higher activity and selectivity toward salicylic alcohol of the non-doped material can be due to both a more localized electron transfer and a longer lifetime of the hole–electron pair. Cu-CN favored the oxidation of hydroxymethyl group. Therefore, the presence of copper can favor different reaction pathways with respect to the non-doped material.

A Study of the Far Infrared Spectrum of N-Acetyl-D-Glucosamine Using THz-TDS, FTIR, and Semiempirical Quantum Chemistry Methods

The far infrared spectrum of N-acetyl-D-glucosamine has been studied by combining THz–TDS and FTIR characterization techniques with theoretical studies based on semiempirical quantum chemistry methods. A strong spectral peak at 60 cm−1 has been identified, which constitutes the main signature of the material in the terahertz band. Calculated molecular vibrations are in good qualitative and semiquantitative agreement with both the THz-TDS and FTIR experiments. In comparison to previous DFT-based studies, the semiempirical approach chosen herein, suitable for parallel multi-core and GPU acceleration, allows for a full study using periodic boundary conditions and no further approximations within a constrained computing time.

Copper complexes within the supramolecular solid structure of cyanuric acid and melamine

ABSTRACT A complex of copper sulfate was formed by impregnation of the cyanuric acid melamine adduct (CAM) with a solution of copper (II) sulfate. A thermal treatment at 250°C of the dried compound delivered a greenish powder. The UV-Vis spectroscopy showed that an absorption around 700 nm is compatible with a copper (II) sulfate complex coordinated inside the supramolecular structure of CAM. No copper or copper oxide particles were found by means of either transmission or scanning electron microscopy. X-ray photoelectron spectroscopy showed that on the surface there was a considerable amount of Cu(I) (66%) probably coordinated also inside the CAM channels. A brief catalytic test showed the ability of the copper complexes to oxidize sucrose to gluconic acid.